The next most frequent is that the device paired Ok, but the connection between the app and the device is frequently lost, and re-connection is difficult.

1. With the app closed, use the Android system Settings, and tap Bluetooth to enter the BT management, ready to turn Bluetooth On.

2. "Start" the car and let it get Ready to drive. Turn Bluetooth On in your phone.

3. Then, quickly plug the ELM327 device into the car's OBD connector. Assuming no BT devices have been discovered or paired, the phone searches for discoverable BT devices. Otherwise, ask the phone to search.

4. When the phone discovers a new (new MAC address) ELM327-type Bluetooth device (often called OBDII), it appears on a list, as not yet paired. Quickly tap the item on the list, enter the pairing code (most often 1234, rarely 0000, and very rarely 6789), and attempt to pair with the ELM327 device. If successful, the listing will show paired, but not connected. If not successful, try to enter the pairing code again.

5. If the second try fails, unplug the ELM327 device dongle and start step 3 again.Sometimes the pairing must be done within the first few (maybe 30) secondsafter the dongle is plugged in.

6. Successfully paired, you can turn your phone's Bluetooth Off, since the LEAF Battery app will turn it On when needed. You can now run the LEAF Battery app and you should see live data in just a few seconds.

---------Notes: If you have trouble, try to get with another LEAF Battery app user, and see their system working on their car, try their system on your car, try your phone with their ELM327 device, and finally try your ELM327 device again.

The most often problem is a stubborn ELM327-type clone device, even an "identical" one from the same supplier. Sometimes you will get different circuitry inside the device, or different firmware, in devices from the same vendor.

Clone firmware 1.5 is to be preferred, I think. Genuine ELM327 devices have 1.4b as their latest version, I think.

Last edited by garygid on Wed May 15, 2013 8:08 am, edited 2 times in total.

With a 2 pole double throw switch, possibly a slide switch because it typically has a much lower profile inside the case, try to figure where to mount it so that it does not block the Bluetooth antenna, and is clear of the inside circuitry. Also, it should be located where you can operate it while the device is plugged in.

No, I do not yet have a good suggestion for this part.

---------Each side of the double throw switch has pin 1, a common (pin 2) , and pin 3. Call the two sides of the switch A and B.

The wire going to pin 14 should be disconnected from pin 14 and connected to A2. The wire going to pin 6 should be disconnected from pin 6 and connected to B2.

Connect A1 to pin 14, and then connect A3 to pin 12. Connect B1 to pin 6, and then connect B3 to pin 13.

Check your work, mount the switch, re-assemble, and check your work again before re-installing the cover on the ELM327-type device.

--------If you had a 3-position (sometimes called On-Off-On) , 3-pole switch, ou could wire the Off position to turn the power off, so you could have EV-CAN, Off, and CAR-CAN.

I would like to get some feedback about whether this statement in the Wiki (under Precautions) is still the best description:

"There is conflicting information about whether leaving the ELM327 scanner plugged in draws enough current to run down the 12 volt battery. There are a couple of reports of batteries going down to 8 volts when the scanner was plugged in overnight. However, one of the reporters did more testing and concluded that the problem was related to having the ELM327 plugged in and having the phone on with the Leaf Battery Application running and communicating with the scanner. When he exited the Leaf Battery Application, he found no significant decrease in voltage for the 12 volt battery (the OBD port does not run off the traction battery)."

I have left me ELM327 plugged in for a couple of days (phone was not connected with scanner, Leaf battery app was not running) without problems. Is there a consensus that the ELM327 can be left plugged in as long as it isn't communicating with the phone? Suggestions for revising this portion of the Wiki?

Over a week now plugged in with no change in battery voltage. However, I drive it almost every day so I'm not sure about long term without driving it at least every other day. I plan on installing a sliding switch and switching the always on wire.